Internal-combustion engine



June 7, 1927.

E. SOKAL INTERNAL COMBUSTION ENGINE Filed 001;. 18. 1926 INVENTOR.

- Patented June 7, 1927.

UNITED STATES PATENT OFFICE.

EDWARD SOKAL, OF BROOKLYN, NEW YORK, ASSIGNOR TOAMERICAN KATALITE COB-PORATION, OF BROOKLYN, NEW YORK, A CORPORATION OF DELAWARE.

IHTEBNAL-COMBUSTIOfi ENGINE.

Application med October 1a, 1926. Serial in. 142,247.

This invention relates to intenal combustion engines, to correlatedimprovements and discoveries whereby and wherewith the operation thereofis enhanced, and more par- 5 ticularly to the prevention of detonationin the combustion chamber thereof.

An object of the invention is directed to the provision in an-internalcombustion engine of an improved detonation counteractant.

Another object is to proyide an improved method of permanentlypreventing detonation in an internal combustion engine.

A further object is to provide an improved l5 coating composition whichmay be ailixed to the walls of the combustion chamber of an internalcombustion engine to prevent detonation therein.

In my co-pending application, Serial No. 42,583, filed July 9, 1925, Ihave shown that the tendency toward detonation in an internal combustionengine, particularly the pronounced tendency thereto in high compressionengines, may be counteracted by fixedly disposing within the combustionchamber of the engine a material capable of undergoing a reversibleendothermic, i.-e., heat-absorbing, change within the range oftemperatures and amid the other conditions existent in the engine duringoperation, by means of which a cooling effect is exerted upon thegaseous mixture within the chamber with a resultant counteraction ofdetonation.

\Vhile it is well recognized that detonabustion chamber can becounteracted by cooling the mixture, no theory offered in explanation ofthis phenomenon has been universally acce ted. It is my view thatdetonation. or necking, in internal combustion engines, is mainly due toa decomposition or breaking down of the unburned fuel, or in otherwords, to the dissociation of the larger molecules of the fuel under theinfluence of heat and pressure into a greater number of smallermolecules, whereby there is caused a sudden rise of pressure. This riseof pressure ma not be indicative of the true condition within the wholebody of the fuel-air mixture. but is rather in the nature of a localizedimpact. This view is supported hv the following considerations: First,the detonating tendency of various fuels is practically a function oftheir then mal stability, for example, the tendency to tion of thegaseous mixture within a comning of the expansion stroke, the peaksbecoming smaller each time, and these rises of pressure are of suchshort duration that the corresponding pressure volume area is too smallto represent an ap reciable amount of useful work and hence theymanifest themselves as destructive impacts. Third, detonation isaccompanied by lost power, deposition of carbon and great loss of heatto the water jacket, which loss of power and deposition of carbon may beconsidered natural results from the decom osition of the fuel, and theloss of heat to t 0 water jacket is probably due to radiation caused byglowing particles of carbon and to the impacts. Fourth, it has beenshown that various factors which cause an increase in the rapidity ofcombustion and make the combustion more complete have a rather ronoundedeffect in counteracting detonation. This would seem to follow as anindirect result of the fact that the molecules of the fuel cannotsimultaneously undergo a reaction of combustion and of decomposition.

In my coending application above referred to, I ave disclosed as anexemplification of a detonation counteractant suitable for use inaccordance with the invention, a material, the melting point of which issuch as to render it capable of undergoing a reversible change fromsolid to liquid state as under the conditions of engine operation, and Ihave particularly suggested the use of lead, antimony and tellurium.

I have now found as a result of continued experimentation that anespecially efiective 1 o detonation counteractant for such use is anon-fugitive, preferably solid, material which is capable under theconditions of engine 0 eration of undergoing a heat-absorbingendothermic) change at the higher 10;; ran e of temperatures existentwithin the com ustion chamber of the engine in which it is employed soas to be converted into a different non-fugitive, preferably solid,chemical material, which latter material is no capable under theconditions of engine opertion of undergoing, at the lower range oftemperatures existent within the combustion chamber, a heat-releasing(exothermic) change so as to restore itself for further heat-absorbingaction. It will be realized from the above that I use a material whichundergoes a reversible chemical change under operating conditions, andthat the original substance disposed within the chamber may contain amaterial appearing on either side of the equation expressing the change,or both. Accordingly, with a view to simplicity of definition, the termchemically endothermically reactive material, as hereinafter employed,is to be understood to designate either a material falling within thedefinition of my improved detonation counteractant given above, or asubstance which is convertible into such material under the conditionsof engine operation. It will be appreciated in this connection thatsince the invention relates to internal combustion engines, the termchemically endothermically reactive material as employed hereinafterincludes only such substances as will undergo the desired reactionswithin the range of temperatures and under the other conditions foundwithin the combustion chamber of the engine in which it is employed.

A chemically endothermically reactive material is partlcularlyadvantageous for use as a detonation counteractant within the combustionchamber of an internal combustion engine because of the marked heat ab--sorption during the endothermic reaction.

with the consequent high cooling effect upon the gaseous mixture.Furthermore. when there is employed a solid material which is convertedinto another solid material under the conditions contemplated by theinvention, a further advantage is to be found in the elimination of anypossibility of the loss of the detonation counteractant by the escape ofa material which has been converted into a fluid state.

In the practice of the invention a material capable of undergoing areversible chemical change which is. endothermic during the powerstroke, when the temperatures within the chamber are the highest and theconsequent tendency toward detonation is the greatest. is fixedlydisposed within the combustion chamber of an internal combustion engine.preferably in the form of, or as an ingredient of, a coating applieirlto certain portions of the walls of said chamber. This coating isespecially eflective when applied to certain of those port-ions of thechamber walls which are hottest during operation, as, for example, theexposed surface of the piston and/or the exposed surface of the exhaustvalves.

The accompanying drawing is a partly memos sectional view exemplifying aform of the invention. In this exemplification a cylinder block 1.together with a high compression cylinder head 2, provides a combustionchamber 3 into which the contacts 4 of a spark plug 5 extend. A portionof the wall of the combustion chamber is provided by a piston head 6 onthe surface of which is a coating 7 containing a relatively permanentchemically endothermically reactive material. Another ortion of the wallof this chamber is provided by the surface of an exhaust valve 8 onwhich there may also be provided a coating 9 which may also contain arelatively permanent chemically endothermically reactive material.

As an exemplification of a suitable material for use in accordance withthe invention, mention may be made of lead carbonate (PbCO This materialis convertible into litharge (PbO) during the power period of engineoperation when the range of temperatures within the chamber is thegreatest. and the resultant lead oxide is reconvertible into leadcorbonate during those intermediate periods of operation when the rangeof temperatures within the chamber is lower. This reversible change maybe represented chemically by the equation PbCO ASPbO CO A ill) whereinthe symbols +A and A indicate within the range of combustion enginetemperatures.

It will, of course, be appreciated that in lieu of a carbonate of anyparticular element there may be employed an oxide thereof which isconvertible into the carbonate under the conditions of engine operation;and the term substance of the carbonate-oxide type as used hereinafter,is intended to refer either to a carbonate which is endothermicallyreactive, or to an oxide, a carbonate, a hydroxide, or other materialwhich is convertible into an endothermically reactive carbonate underthe conditions contemplated by the invention. For example, in lieu of acarbonate of lead, litharge or any other oxide of lead which isconvertible into an endothermically reactive carbonate of lead underengine operating conditions, may be employed. There may also be used'amixture of litharge and lead carbonate in suitable proportions, as forexample, in substantially equal proportions, whereby the advantagesinherent in the use of both mate rials may be utilized.

The litharge possess a somewhat reater initial adhesiveness than thelead car nate, but the presence of lead carbonate in the exposed surfaceof the initial coating, although not indispensable, is desirable,because if litharge is used, its change into lead carbonate being anexpansion in volume, may have a tendency to loosen its contact with thesurface beneath, while in the case of lead carbonate the initial changebeing accompanied by a diminution of volume, there is here by a naturalprovision made for porosity in the coating to take care of anysubsequent changes in volume. It is to be noted in this connection thatthe chemical changes occurring during ordinary operation probably takeplace only in the exposed surface layer of the detonation counteractant,and also that even on this layer each molecule of the material isrobably not converted under ordinary conditions, but that the reactionoccurs merely in a proportion of the molecules sufiicient to exert therequired cooling effect or to restore the material for further heatabsorption, as the case may be.

It is to be understood, moreover, that the invention is in no wiselimited to the use of any particular material or class of materials, butis directed broadly to any relatively permanent material capable ofundergoing, un-

der the conditions of engine operation, a reversible heat-absorbingchemical change; and further that the term relatively permanent isintended to apply not only to the improved detonation counteractant, butalso to the substance into which it is changed during heat absorption. Iw

In order properly to secure it to the chamber walls, the improveddetonation counteractant, in finely divided form,"may be admixed with asuitable binder, such as a silicate. For example, an intimate mixture ofa finely divided chemically endothermically reactive material with asilicate binder may be applied in the form of a coating on the exposedsurface of the piston head, and/or such other portions of the walls asmay be desired. The proportions of active substance to the binder may bevaried to the requirements of the particular case, and it has been foundthat satisfactory results are produced when a mixture containing 25% ofsubdivided litharge, 25% of lead carbonate, and 50% of a silicate isemployed, though these proportions may be varied widely. The applicationmay be accomplished by cleaning the desired surface area, coating sucharea with the detonation counteractant, and baking or setting. Thisprocedure may be repeated if desired until several coats have beenapplied. The amountof the improved detonation cou'nteractant to beapplied in a particular type of engine may be readily determined bysuitable tests indicating the proper surface area to be coated in orderto obtain efficient operation.

At the present time the phenomenon of detonation, or knocking, duringthe operation of internal combustion engines is of much interestbecause, other condtions being equal, it is more pronounced with enginesof high compression ratios. Accordingly this tendency to detonate with agiven fuel becomes practically a limiting factor for improvement in thethermal efiicienc and power output through an increase in thecompression ratio. This is particularly the case with the constantvolume cycle, t e of engine which is used almost exclusive y inautomobiles and in aeroplanes and also to a considerable extent in smallmarine and stationary engines.

It is true that there are other limiting factors, such as loss inmechanical efiiciency, which may offset the gain in thermal elliciencyafter a certain increase in the compression ratio, but the limitationdue to the injurious effects of detonation becomes operative beforethese other limiting factors exert their influence. Accordingly, it willbe apparent that the resent invention, because of the marked eectiv'eness of a chemically endothermically reactive material as adetonation counteractant, will ermit the designing of engines having ahigher comprgalssion ratio than has heretofore been poss1 e.

Among the other advantages arising through the utilization of thedetonation counteractant, mention may be made of the following: lack ofdetonation or knocking,

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lower fuel consumption, more flexible 0 eration of the engine, decreasein carbon e osition, and an increase In the thermal e ciency,particularly in connection with the in which the detonationcounteractant may function, and while it is supported by known facts, itis to be understood, of course, that the operativeness and racticabilityof the invention is not depen out upon or limited in any way by thecorrectness of such theory.

Since certain changes may be made in the detonation counteractant abovedescribed, and difierent embodiments of the invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description shall be interpreted as illustrativeand not in a limitsense. t is also to be understood that the followingclaims are intended to cover all of the generic and specific features ofthe invention herein described, and all statements of the scope of theinvention which, as a matter of language, might be said to falltherebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is:

1. In an internal combustion engine, the combination with a combustionchamber, of a relatively permanent detonation counteractant fixedlydisposed within said chamber, and consisting of a material which ischemically endothermically reactive under engine operating conditions. 7

2. In an internal combustion engine, the combination with a combustionchamber, of a coating disposed on certain of the walls of said chamber,said coatin containing a relatively permanent material which ischemically endothermically reactive under engine operating conditions.

3. In an internal combustion engine, the combination with a combustionchamber, of a coating disposed on certain of those portions of the wallsof said chamber which are hottest under operating conditions, saidcoating containing a solid material capable of undergoing, underoperating conditions, a reversible endothermic chemical change intoother solid material.

4. In an internal combustion engine, a combustion chamber arranged forthe reception of a gaseous mixture and fitted with a piston presentingan exposed surface to the gases in said chamber, said surface comprisinga coating containing a material which is chemically endothermicallyreactive under engine operating conditions.

5. In an internal combustion engine, the combination with a combustionchamber. and of a metallic salt which is chemically endothermicallyreactive under engine operating conditions fixedly disposed within saidchamber.

6. In an internal combustion engine, the combination with a combustionchamber, of an endothermicallv chemically reactive substance of thecarbonate-oxide type fixedly disposed upon certain of the walls of saidchamber.

7 In an internal combustion engine, a combustion chamber arranged forthe reception of a gaseous mixture and fitted with a piston presentingan exposed surface to the gas in said chamber, said surface comprising acoating containing undergoing a reversible changeinto an oxide underengine operating conditions.

8. In an internal combustion engine, the combination with a combustionchamber, of a coating formed on certain of those portions of the wallsof said chamber which are hottest during engine operation, said coatingcontaining an endothermically reactive lead compound.

9. In an internal combustion engine, the

combination with a combustion chamber, of a detonation counteractantfixedly disposed a carbonate capable of within said chamber, saiddetonation counteractant comprising a carbonate of lead.

10. In an internal combustion engine, the combination with a combustionchamber, of a coating formed on certain of those portions of the wallsof said chamber which are hottest during operation, said coatingcomprising normal lead carbonate.

11. In an internal combustion engine, the combination with a combustionchamber, of a detonation counteractant fixedly disposed within saidchamber, said detonation counteractant comprisin litharge.

12. In an internaI combustion engine, the combination with a combustionchamber, 0 a coating formed on certain of the walls of said chamber,said coating containing a carbonate of lead and litharge.

13. As an article of manufacture, a piston head arranged for use withinan internal combustion engine, the pressure surface thereof havingformed thereon a coating containing a chemically endothermicallyreactive lead compound of the carbonate-oxide yp 14. In an internalcombustion engine, the combination with a combustion chamber, of anendothermically chemically reactive lead compound of the carbonate-oxidetype fixedlv disposed within said chamber.

15. In an internal combustion engine, the combination with a combustionchamber, of a coating formed on certain of the walls of said chamber,said coating containing a rela tively permanent material which ischemically endothermically reactive under engine operating conditions,and a binder.

16. In an internal combustion engine, the combination-with a combustionchamber, of a relatively permanent material which is chemicallyendothermically reactive under engine operating conditions, in fineldivided form, intimately admixed with a silicate binder.

17. In an internal combustion engine, the

combination with a combustion chamber, of a coating formed on certainportions of the walls of said chamber, said coating contain ing acarbonate of lead and a silicate.

18. A method of effectingv improvement in the operation of an internalcombustion engine, which com rises permanently exposing within the comnstion chamber thereof a material which is chemically endothermical- 1yreactive under engine operating conditions.

19. A method of counteracting detona-' exposing to such charges a solidmaterial capable of undergoing, under engine operating conditions, areversible endothermic chemical change into other solid material.

20. A method of effecting improvement in the operation of an internalcombustion engine, which comprises forming on certain of those portionsof the wall of the combustion chamber of the engine which are thehottest during operation, a coating containing a relative y permanentmetallic carbonate which is chemically endothermically reactive underengine operating conditions. i

i In testimony whereof I aflix my signature.

EDWARD SOKAL.

19. A method of counteracting detona-' tion of the successive fuelcharges in the combustion chamber of an internal combus tion engine,which comprises permanently Patent No. 1,631,703.

exposing to such charges a solid material capable of undergoing, underengine operating conditions, a reversible endothermic chemical changeinto other solid material.

20. A method of effecting improvement in the operation of an internalcombustion engine, which comprises forming on certain of those portionsof the wall of the combustion chamber of the engine which are thehottest during operation, a coating containing a relatively permanentmetallic carbonate which is chemically endothermically reactive under enine operating conditions.

In testimony whereof I afiix my signature.

EDWARD SOKAL.

V Granted June 7, 1927, to

EDWARD SOKAL.

It is hereby eertified that error appears in the printed specificationof the abovenumbered nt requiring correction as follows: Page 1, line 1,for the misspelled word intend] read internal, and line 49, after theword true insert the word pressure; page 3, line 81, for the mi and thatthe said Letters Patent shou d conform to the record of the case in thePatent Oflice.

that the same ma lied word condtions; read conditions;

be read with these corrections therein Signed and se ed this 19th day ofJuly, A. D. 1927.

M. J. MOORE, Acting Uonmu'aaimwr of Patents.

Certificate of Correction.

Patent No. 1,631,703. Granted June 7, 1927, to EDWARD SOKAL It is herebycertified that error appears in the printed specification of theabovenumbered patent requiring correctlon as follows: Page 1, line 1,for the misspelled word intenal read internal, and line 49, after theword true insert the word pressure; page 3, line 81, for the misspelledword condtions; read conditions; and that the said Letters Patent shouldbe read with these corrections therein that the same ma conform to therecord of the case in the Patent Ofllee.

Signed and sued this 19th day of July, A. D. 1927.

[ l M. J. MOORE,

Acting C am/missionaof Patents.

